It is an unwanted statistic for the tournament, which has seen 10 withdrawals in the singles competition overall, with the record currently held by the 2011 U.S. Open when 17 competitors were forced out with injuries.

Azarenka, the World No.2 suffered an injury to her right knee during Monday's first round win over Portugal's Maria Joao Koehler and withdrew just minutes before Wednesday's tussle with Italy's Flavia Pennetta on Centre Court.

The Australian Open champion, who has reached the semifinal stage in each of the past two years, was clearly unhappy with the conditions of the court and hit out after seeing her Wimbledon dream crushed.

But the All England Lawn Tennis And Croquet Club responded immediately in a statement following Azarenka's attack.

"There have been no changes in the preparation of the courts and as far as we are aware the grass court surface is in excellent condition," it read.

"In fact we believe that it is drier than last year when the prevailing conditions were cold and wet.

"A grass court is a natural surface and will generally be slightly more lush in the first couple of days. Although a number of players have withdrawn injured, only one player has attributed this to slipping over on court."

CEO Richard Lewis also released a statement late Wednesday following the surprise number of withdrawals.

"There has been a high number of withdrawals at the Championships and we sympathize with all the players affected," he said on the tournament's official website.

"The withdrawals have occurred for a variety of reasons, but there have been some suggestion that the court surface is to blame. We have no reason to think this is the case. Indeed, many players have complimented us on the very good condition of the courts.

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"The court preparation has been to exactly the same meticulous standard as in previous years and it is well known that grass surfaces tend to be more lush at the start of an event.

"The factual evidence, which is independently checked, is that the courts are almost identical to last year, as dry and firm as they should be, and we expect them to continue to play to their usual high quality."

Meanwhile, Tsonga, who had hoped to challenge for the men's title, was forced to retire during his contest against Ernests Gulbis of Latvia after complaining of knee and wrist problems.

But the Frenchman, who had completed three sets before retiring, refused to blame the court conditions.

"There is nothing about this court. They're great," he told reporters.

"The only thing we can say is the weather we have had for a couple of weeks is humid and cold and windy sometimes."

Elsewhere, Darcis, ranked 135 in the world, suffered an injury to his right shoulder after a fall during his landmark win over Nadal.

The 29-year-old had been set to face Poland's Lukasz Kubot in the second round, but failed to overcome the problem in time.

"I think when you beat a guy like Rafa in the first round, you want to show more, you want to play more matches. I was playing maybe the best tennis in my life here," Darcis told reporters.

"So not to go on the court today, it's the biggest disappointment I have had."

John Isner was another casualty after pulling out of his clash with France's Adrian Mannarino just two games into his second round game.

Isner, who won the longest match in the history of the tournament against Nicolas Mahut in 2010, suffered a leg injury while serving early on.

"I just went to serve, and it was as I landed on my left leg, like I have done 20 million times playing this game. I just felt this sharp pain," 18th seed Isner told reporters.

"It just grabbed really badly and I knew I was in serious trouble then. I knew at that point it was not likely I was going to be able to play."

There was also bad news for 10th seed Cilic, who had hoped to reach the later stages of the tournament following his run to the final at the Queen's Club last week.

The Croatian had hoped to face France's Kenny de Schepper before withdrawing with a knee injury, while Radek Stepanek was forced to retire at 6-2 5-3 down to Poland's Jerzy Janowicz after pulling his left hamstring.